Fix NGUI based buttons when using touchscreen

[drojf]

Problem

A user reported that touchscreen doesn't work properly with the mod.

When you try to click a button on the title menu, it would flash as if you hovered over it, but would not do anything.

Only certain buttons (which turned out to be NGUI based) have this issue.

I tested and this issue happens even on the unmodded game (as I expected, as we have not modified input handling much in our mod)

Reason

This is because the input handling for NGUI based buttons in the game code first checks whether it is a left click, via the UICamera.currentTouchID variable with the code UICamera.currentTouchID == -1 (-1 indicates mouse left click)

For example:

private void OnClick()
{
    if (UICamera.currentTouchID == -1 && !(cooldown > 0f))
    {
...

However, when you touch a touchscreen, it returns a zero-or-higher number (eg 0,1,2,3 ...) representing the "fingerID". This causes the touch to be ignored.

See https://docs.unity3d.com/ScriptReference/Touch-fingerId.html

You're supposed to use this fingerID as in index to lookup the properties of the current touch

Fix

Changing to UICamera.currentTouchID >= -1 should allow both mouse left clicks, and any touches to activate NGUI buttons.

However there may be other places in the code which have similar problems, I haven't checked or tested it.

NGUI UICamera.currentTouchID mapping

I think the mapping of the UICamera.currentTouchID variable (from NGUI) is something like:

-3 = middle mouse
-2 = right mouse click
-1 = left mouse click
0 = touch index 0
1 = touch index 1
etc...